Caching directories

[Pavel Roskin <proski@gnu.org>]

Hello!

I'm thinking of moving cg-clean functionality to git.  After having
switched to StGIT, it's the last cogito command I'm still using.  I
think git can go it much better, since it's a recursive command
traversing the whole repository.

To be safe and useful, the new command should distinguish between
tracked and untracked directories.  Untracked files in tracked
directories are usually the first target for cleaning, as they are
mostly automatic backups and temporary files.  Untracked directories are
more likely candidates to be preserved, as they can hold external
sources, build output, extensive test data etc.

cg-clean considers a directory untracked if it has no cached files in
it.  This carries a significant speed penalty, even if not coded in
bash.

Maybe it's time to start caching directories in git?  I mean,
directories corresponding to tree objects could have their stats
recorded in the cache.  This would allow to distinguish between tracked
and untracked directories without scanning them recursively.

-- 
Regards,
Pavel Roskin